In heat exchangers of the type considered herein there is usually provided a pair of spaced header plates between which extend spaced tubes for conveying a first fluid such as a liquid between spaced tanks of which the header plates are parts. A second fluid such as air is then forced over and between the tubes and usually in contact with serpentine fins for cooling the liquid flowing through the tubes. An automotive radiator is a good example of such an exemplary heat exchanger.
Many of these heat exchangers particularly where the headers and tubes are constructed of brass and the interconnecting fins of copper are deficient in strength because the joints are customarily solder and have poor creep and fatigue properties. This invention both in structure and method avoids these difficulties by providing a primary load bearing joint such as weld metal joining the tubes to the headers at their areas of contact or of close proximity and then a thin sealant sealing against leakage any small leakage openings such as cracks, fissures, pin holes or the like that may be present.
The most pertinent prior art of which I am aware are the following U.S. Pat. Nos. 2,270,864; 2,914,346; 3,078,551; 3,349,464; 3,496,629; 3,633,660; 3,689,941; 3,710,473; 3,750,747 and 3,763,536. Although many of these patents illustrate the problems of cracks, fissures and similar leaks in welded joints, none of them teach the solution to this problem of providing in the heat exchanger combination a thin sealant.